Recently, as a result that wireless access points (hereinafter referred to as “AP”) have been spread, it is natural that the terminals such as smartphones communicate with the other parties while changing the wireless APs and wide area wireless connection of a communication carrier. In such an environment, a communication condition is influenced by the connection number of terminals using a same wireless medium and a neighboring radio wave circumstance, so that a communication quality varies according to a place and time, and the communication becomes intermittent.
For example, when a user's terminal communicates with a server on the internet while changing an AP to be linked during the movement, if there is a large amount of data of the communication and a staying time of the terminal within a link available range of the AP is short, the communication during the connection is disconnected on the way and hence retrial of the communication is needed after re-link with another AP.
In contrast, it is considered to provide an application of the terminal with a resistance to delay and disruption of the communication (see e.g. Patent Document 1: Japanese National Publication of International Patent Application No. 2015-528222). There is known a Delay/Disruption Tolerant Networking (DTN) as a technique enabling smooth communication in the environment where the communication becomes intermittent. The standardization of this technique is promoted by IETF (The Internet Engineering Task Force), and a bundle protocol to be applied to the DTN is specified in RFC (Request For Comments) 5050, for example.